全文获取类型
收费全文 | 1641篇 |
免费 | 29篇 |
国内免费 | 12篇 |
专业分类
教育 | 1119篇 |
科学研究 | 248篇 |
各国文化 | 24篇 |
体育 | 129篇 |
综合类 | 5篇 |
文化理论 | 10篇 |
信息传播 | 147篇 |
出版年
2023年 | 10篇 |
2022年 | 16篇 |
2021年 | 38篇 |
2020年 | 42篇 |
2019年 | 57篇 |
2018年 | 72篇 |
2017年 | 97篇 |
2016年 | 61篇 |
2015年 | 49篇 |
2014年 | 71篇 |
2013年 | 264篇 |
2012年 | 63篇 |
2011年 | 64篇 |
2010年 | 61篇 |
2009年 | 47篇 |
2008年 | 53篇 |
2007年 | 48篇 |
2006年 | 35篇 |
2005年 | 46篇 |
2004年 | 29篇 |
2003年 | 34篇 |
2002年 | 31篇 |
2001年 | 32篇 |
2000年 | 26篇 |
1999年 | 29篇 |
1998年 | 8篇 |
1997年 | 8篇 |
1996年 | 23篇 |
1995年 | 15篇 |
1994年 | 12篇 |
1993年 | 5篇 |
1992年 | 16篇 |
1991年 | 18篇 |
1990年 | 12篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 10篇 |
1986年 | 10篇 |
1985年 | 19篇 |
1984年 | 16篇 |
1983年 | 14篇 |
1982年 | 15篇 |
1981年 | 7篇 |
1980年 | 9篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1975年 | 11篇 |
1974年 | 6篇 |
1973年 | 7篇 |
1971年 | 7篇 |
排序方式: 共有1682条查询结果,搜索用时 15 毫秒
81.
82.
<正> 全国化工院校情报中心站第四届年会于1988年10月17日-21日在武汉化工学院召开。中心站21个成员单位的代表出席了会议。化工部情报所的有关同志参加了会议。湖北省及武汉市图书馆情报界的知名人士、武汉化工学院领导等均到会致词祝贺。年会的主要议程有:一、就高校情报工作的服务方向、情报有偿服务、情报教学等方面的改革进行了广泛的交流和探讨。华东化工学院和青岛化工学院的代表介绍了图书馆实行定编定岗、优化组合、工资包干和情报实行定额承包、面向企业的改革尝试,引起了代表们的极大兴趣和热烈讨论。 相似文献
83.
84.
What happens when the only staff member who knows how to do a particular task is no longer available? Using NASIG’s Core Competencies for Electronic Resources Librarians, the Electronic Resources and Serials Department of Auburn University set out to tackle the problem of the indispensable staff person, and discovered that expertise is never fully achieved, and competence is always a work in progress. 相似文献
85.
Fengjiao Lyu Manqi Xu Yunfeng Cheng Jinghang Xie Jianghong Rao Sindy K. Y. Tang 《Biomicrofluidics》2015,9(4)
This paper describes a method for the quantitative detection of cells expressing BlaC, a β-lactamase naturally expressed by Mycobacterium tuberculosis, intended for the diagnosis of tuberculosis. The method is based on the compartmentalization of bacteria in picoliter droplets at limiting dilutions such that each drop contains one or no cells. The co-encapsulation of a fluorogenic substrate probe for BlaC allows the quantification of bacteria by enumerating the number of fluorescent drops. Quantification of 10 colony forming units per milliliter is demonstrated. Furthermore, the encapsulation of single cell in drops maintains the specificity of the detection scheme even when the concentration of bacteria that do not express BlaC exceeds that expressing BlaC by one million-fold. 相似文献
86.
H. A. Guidobaldi Y. Jeyaram C. A. Condat M. Oviedo I. Berdakin V. V. Moshchalkov L. C. Giojalas A. V. Silhanek V. I. Marconi 《Biomicrofluidics》2015,9(2)
Many self-propelled microorganisms are attracted to surfaces. This makes their dynamics in restricted geometries very different from that observed in the bulk. Swimming along walls is beneficial for directing and sorting cells, but may be detrimental if homogeneous populations are desired, such as in counting microchambers. In this work, we characterize the motion of human sperm cells ∼60 μm long, strongly confined to ∼25 μm shallow chambers. We investigate the nature of the cell trajectories between the confining surfaces and their accumulation near the borders. Observed cell trajectories are composed of a succession of quasi-circular and quasi-linear segments. This suggests that the cells follow a path of intermittent trappings near the top and bottom surfaces separated by stretches of quasi-free motion in between the two surfaces, as confirmed by depth resolved confocal microscopy studies. We show that the introduction of artificial petal-shaped corrugation in the lateral boundaries removes the tendency of cells to accumulate near the borders, an effect which we hypothesize may be valuable for microfluidic applications in biomedicine. 相似文献
87.
L. Yu S. M. Grist S. S. Nasseri E. Cheng Y.-C. E. Hwang C. Ni K. C. Cheung 《Biomicrofluidics》2015,9(2)
Creating multicellular tumor spheroids is critical for characterizing anticancer treatments since they may provide a better model of the tumor than conventional monolayer culture. Moreover, tumor cell interaction with the extracellular matrix can determine cell organization and behavior. In this work, a microfluidic system was used to form cell-laden core-shell beads which incorporate elements of the extracellular matrix and support the formation of multicellular spheroids. The bead core (comprising a mixture of alginate, collagen, and reconstituted basement membrane, with gelation by temperature control) and shell (comprising alginate hydrogel, with gelation by ionic crosslinking) were simultaneously formed through flow focusing using a cooled flow path into the microfluidic chip. During droplet gelation, the alginate acts as a fast-gelling shell which aids in preventing droplet coalescence and in maintaining spherical droplet geometry during the slower gelation of the collagen and reconstituted basement membrane components as the beads warm up. After droplet gelation, the encapsulated MCF-7 cells proliferated to form uniform spheroids when the beads contained all three components: alginate, collagen, and reconstituted basement membrane. The dose-dependent response of the MCF-7 cell tumor spheroids to two anticancer drugs, docetaxel and tamoxifen, was compared to conventional monolayer culture. 相似文献
88.
题目:一种支持产品平台设计的多准则模块划分方法 总被引:2,自引:0,他引:2
目的:研究多准则约束下的产品模块划分方法,为企业建立稳健的模块化产品平台奠定基础。方法:采用改进的多目标进化算法对建立的多准则模块划分数学模型求解,并采用模糊集合评价机制进行最优解的寻取,得到基于多准则模块划分方法的产品模块划分结果。结论:通过改进的多目标进化算法求解多准则模块划分模型,能够得到有效支持产品平台设计的产品模块划分方案。通过与已有优化方法的比较验证了本文提出的多准则模块划分方法的优越性。 相似文献
89.
Computational thinking (CT) is vital for success in numerous domains. However, the nature, definition, and scope of CT are ill-defined, and research on how best to develop CT is very limited. This study focused on how thinking styles and STEM attitudes have effects on computational thinking. Using a proportionate stratified random sampling procedure, 1195 students from two universities were surveyed. A structural equation modeling analysis showed that students' thinking styles and STEM attitudes directly predicted their computational thinking skills and that thinking styles mediated the relationship between STEM attitudes and computational thinking skills. Thinking styles and STEM attitudes are strong predictors of CT skills. Based on the results, we recommended that the conceptualization of CT be broadened to reflect its trans-disciplinary nature within the context of STEM education. This study adds to the limited theoretical understanding of CT and CT-predictors in higher education, which has been studied much less than in K-12 education. 相似文献
90.
Ling-Xiang Tang Shlomo Geva Andrew Trotman Yue Xu Kelly Y. Itakura 《Information processing & management》2014
Cross-Lingual Link Discovery (CLLD) is a new problem in Information Retrieval. The aim is to automatically identify meaningful and relevant hypertext links between documents in different languages. This is particularly helpful in knowledge discovery if a multi-lingual knowledge base is sparse in one language or another, or the topical coverage in each language is different; such is the case with Wikipedia. Techniques for identifying new and topically relevant cross-lingual links are a current topic of interest at NTCIR where the CrossLink task has been running since the 2011 NTCIR-9. This paper presents the evaluation framework for benchmarking algorithms for cross-lingual link discovery evaluated in the context of NTCIR-9. 相似文献